Syringe



Patented Mar. 24, 1931 UNITED STATES PATENT OFFICE WILLARD H. BROCKWAY, OF NEEDHAM, MASSACHUSETTS, ASSIGNOR TO MACGREGOR INSTRUMENT COMPANY, OF NEEDHAM, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS SYRINGE Application :filed February 9, 1928. Serial No. 252,984.

In certain types of syringes, notably those for surgical and dental use, the provision for a frictional control of the plunger .is a factor greatly desired. As my present invention has been developed particularly with such types of syringe in View, I shall discuss it in connection therewith as it affords a convenient i. illustration of the principles involved and is contact with the fluid contents and because `the position o-f the thumb piece is changed and not easily re-engaged Without shifting the position of the hand.

For the purposes of illustration I have shown in the accompanying drawings a form of syringe embodying my invention. To these drawings I have made reference by characters applied throughout the specification.

In the drawings Fig. 1 is a general view of my syringe.

` A Fig. 2 is an enlarged fragmentary sectionv ofv a preferred form thereofshowing the de-v vice in frictioning position.

Fig. 3, a similar view of a modified form of my invention in non-frictioning position showing the raising of the plunger, and

Fig. 4, a section on the line 4-4 of Fig. 3.

I have indicated at l the barrel which in this form of syringe is a glass tube into which is closely fitted a plunger 2. The barrel l has the usual fittings and needle attachment at its lower end, but these need not be considered as they areV not involved in my presentV invention.

Ina preferred form of embodiment of my invention I provide on the upper end of the barrel l a threaded collar cemented to the glass barrel. This collar is screwed into a Vcap 4 which carries the linger rings 5. The

cap 4 is provided with a shoulder 6. This may be a bushing pressed into and becoming a part of the cap 4 or may be produced as a part of the cap casting. This shoulder 6 forms a bearing for the plunger 2 and in this form of my device has an inclined bearing surface on its inner face.

Betweeny the shoulder 6 and the top of the barrel `l is left a space which constitutes an annular channel 7 in the body or barrel of the syringe when considered as a whole. It will be understood that this channel 7 may be variously formed but in the construction shown is very cheaply and conveniently made by this spacing of the glass barrel l from the shoulder 6.

Located within this space 7 is a friction piece 8. This piece 8 is in the form shown a split ring or annulus the faces of which are parallel and each edge of which is in a plane perpendicular to its bore which receives the plunger with a close but free fit. The ring 8 therefore with its slight clearance on the plunger 2', when the ring 8 is alined with the axis of the plunger', permits the free movement of the plunger through the ring. This is true generally on the delivering stroke of the plunger as well as on the upward or charging stroke. For the reasons stated above, however, it is not desirable that the plunger be free from the barrel in all positions notably in inverted positions.

Still referring to the lform of my invention shown in Fig. 2 on the inward or delivery stroke of the piston 2, the friction ring 8 finds bearing on the top of the barrel and its axis is perpendicular to the axis of the piston. When, however, the syringe is tipped or inverted or there is any sudden pull on the plunger 2 the friction ring S tilts and assumes the frictioning position indicated in Fig. 2 and rests against the inclined shoulder 6 so that its axis isat an angle to the axis of the plunger and its periphery is brought into contact with the plunger 2. This provides a frictional engagement ofthe edges of the ring 8 with the plunger walls so that considerable force is needed to withdraw the plunger 2. Any likelihood of the plunger 2 lili" slipping or dropping from the barrel is entirely obviated.

In the modifications shown in Fig. 3 instead of providing an inclined or angular surface on the inside of the cap 4, as, fon'example, the shoulder 6, I provide a friction ring such as that indicated at 8. This friction ring 8 has anannular or inclined plane,

on one edge and is shown` in non-frictional position in Fig. 3. In Operation, the ring is placed in the recess 7 with its inclined face outward. If the syringe is inverted this inclined face finds bearingagainstthe horizony tal wall l of the cap 4 placing the ring in frictioning position similary to that illustrated in- Fig. 2. This same position is assumed by the ring 8 on a sudden withdrawal stroke of the plunger 2, the axis of the ring then being at an angle to the axis` of the plunger andi its periphery engaging the plunger. It will 'be understood that either embodiment of my invention provides a highly satisfactory operating condition. The plunger is entirely free to move inwardly or outwardly oiering no resistance at all to the thumb pressure f the operator, but any upsetting or accidental deviation will cause the ring to assume frictioning position and hold the plunger locked until 'deliberately adjustn ed by the user.

In the foregoing I have discussed my llock in its purely auto-matic function. There as, however, another importan-t phase of mymvention which relates to thevcontrolvof the i plunger lock so that it canv be rendered inoperable when desired. Itis a combinative feature of great importance but one` that may be omitted in types of syringes where control of the lock is not necessary.

In certain Work, notably inl local anesthesia, it is desired to operate a 'syringe intermittently during perhaps a very extended.

operat-ion and with the patient in a great variety of postures. It is therefore impor- 'tant that the syringe lock itself' 'when not in operation, and yet be readily operated by the user regardless of the posture of 'the patient.

To this end my invention contemplates the provision of a positive control as illustrated in Fig. 2. In this figure I have shown the cap, as apertured ati) foi` the reception of'a plunger l0 controlled by a spring 11. This spring il fits within a channel or groove in the finger ring for apart of its circumfer-Y ence and then depart-s from its inner surface with a sufficient clearance so. that when the operators finger is Within the ring the plunger l0- is projecting into the `cavity y7 behind the ring Svor 8. asthe-structure might be. This prevents the ring fromtilting and insures a free movement ofthe plunger during operation. A's'soon as the operators ffn. ger is withdrawn from thering thefplgunger l0 is removed from its position behind the locking piece and it may tilt to lock the plunger in place.

Various modifications may obviously be made in the construction of the syringe and the form shown will obviously be modiiied in caseof different types and differentclasses of syringe. My invention is furthermore capable of application to movingI parts in other than syringes.' All such modifications,

variants and adaptations are to be construed within the purview of my invention ifconsistent with the appended claims. V

lVhat I therefore claim and desire to secure by Letters Patent is:

1. In a syringe, a barrel,` a: plunger, vand 30 a plunger lock comprising a relatively flat plunger loc-king member having a free iit on the plunger, and a rear stop for the locking member, said member and stop having a plane of contact o-ut of the perpendicular of' 85 the plunger axis.

2. In a syringe, a recessed barrel, Ia plunger moving in said barre-l, a plunger lock in said recess and means for rendering said lock ineffective comprising a spring controlled V member adapted to be projected .into said recess behind said lock.

3. In a syringe, a recessed barrel and a plunger moving in said barrel, the wallsA of said barrel providing a plungerrbearing, said" '95 recessed portion having a face inclined tothe plunger axis, a. friction ring di'sposedin said recess adapted to rest von said inclined face when said syringe is tilted from the vertical whereby its edges frictionally engage said channel in said barrel, a plunger engaging frictional mem-ber in said channel and means lfor rendering said frictional member .ineii'ee tivecomprising a spring controlled member located in said aperture in said barrel said,

Yspring -iitting withinl said groove in said' y115 fingerV ring for a part of its circumference and then departing from its inner surface with a sufficient clearance. whereby when the operators finger is Within the ring said spring.

controlled member is projected through said aperture .into said channel 4behind saidfrictional ring thus ypreventing engagement thereon with said plu-nger.

5.. In a syringe, a barrel, a plunger, a.

plunger locking ring having a free fit on the plunger and a rear stop for the locking-ring,

vsaid ring and vstop having avplane of Contact Vout-of the, perpendicular of the plunger axis.

6. Ina syringe, ay barrel, a plunger disposed therethrough, a recessed rear stop for said plu-nger 105 the plunger, and a locking member in said recess having a free fit on the plunger, said plunger stop and locking member having an inclined plane of contact out of the perpendicular of the plunger axis when said syringe is in other than downwardly inclined position.

7 In a syringe, a barrel, a plunger and a tiltable gravity plunger locking ring having a free fit on the plunger when the syringe is in downwardly inclined position, and a friction lit when the syringe is upwardly inclined.

8. In a syringe, a barrel, a plunger and a tiltable gravity plunger locking ring having a free it on the plunger in one position and a friction it in its other position.

9. In a syringe, a barrel, a plunger and a gravity plunger lock having a plunger receiving bore normally coaxial with the plunger but angularly disposed thereto when the lock is tilted upon the inversion of the syringe.

10. In a syringe, a barrel, and a plunger, said barrel having a plunger encircling recess, a gravity plunger lock having a free lit on the plunger and tiltably positioned in said recess, said lock and recess having conaclting surfaces in one position of tilt of the 11. In combination an hypodermic syringe having a needle and a fluid expelling means, and means comprising a single member located adjacent the latter to permit movement toward the needle and to grip and frictionally bind the fluid expelling means against movement away from said needle, thereby to prevent suctional action through the needle.

In testimony whereof I affix my signature.

WILLARD I-I. BROCKWAY. 

